Hydraulic pit props



l Dec.'17, 1957 w. LBBE HYDRAULIC PIT lPRoPs Filed 'April e, 195o W/LHE'ILM oE DECEASEQ B7 ,4e/wml OBBE ADMINISTRATOR United States Patent HYDRAULIC PIT PROPS Wilhelm Lbbe, deceased, late of Oberaden, Germany,

by Armin Dieter Lbbe, administrator, Oberaden, Germany Application April 6, 1950, Serial No. 154,411

Claims priority, application Germany April 7, 1949 1 Claim. (Cl. 248-354) Known hydraulic pit props comprise a cylinder, which generally acts as the foot of the prop and in which a piston forming the upper portion of the prop is guided. It has already been proposed to connect the prop to a pipe supplying water under pressure and to leave the connection between the pipe and the prop opened during the period the latter is standing. The supporting capacity of the prop is then permanently equal to the piston area multiplied with the pressure in the pipe. If the roof subsides, the prop is shortened, but the supporting capacity is not altered.

Hydraulic pit props are also known in which a certain water supply is contained in the prop and is adapted to u be forced underneath the piston by the aid of a high pressure pump arranged on the prop, so that the piston is forced out and pressed against the roof. The placing stress for such props merely depends upon the pressure up to which the water is raised by means of the pump.

The consequence of this will be that practically all the props standing in one mine working have different placing stresses. An even greater disadvantage however, is that the operation of the pressure pump upon setting up any one prop is time-consuming and troublesome and generally lasts disproportionally longer than the placing of a wooden prop or of a normal iron prop in which the upper and lower portions of the prop are clamped relatively to one another in the extended position by a friction lock.

The problem forming the basis of the present invention is to support the roof of a mine working by hydraulic pit props in such a manner that the placing pressure of all individual props has as far as possible the same value, and particularly that the placing of the individual props in any desired sequence can be carried out without diic'ulty and in the shortest possible time and finally, that the maximum load which can be taken up by the prop is substantially above the placing stress, but can on the other hand be so regulated that deformation or destruction of the prop is avoided.

According to the present invention, a hydraulic pit prop not only has a check valve through which the pressure medium is introduced from the outside from a pipe and which can be discharged again upon knocking away, but is also provided with an excess pressure or relief valve by means of which the maximum load isy determined. In this arrangement, the pressure medium hose used for the lling of the prop conveniently carries a connection member so that it may be coupled with any prop to be erected. Such a connection member may be made inthe form of a lever so that after having been guided on to the prop by exerting a pressure on its long lever arm, the end of the short arm can be pressed so firmly and tightly against the inlet opening of the prop that the pressure medium can be passed into the prop through the short lever arm without any screwing action being necessary.

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For this purpose, the long lever arm of the connection member may be constructed as a tube into which the hose opens. The connecting member advantageously has a valve for controlling the ilow of pressure medium.

A pin is advantageously arranged at the outlet opening of the connecting member, so that the check valve in the inlet opening of the prop can be lifted from its seating when the connecting member is coupled with the prop. This arrangement guarantees that the pipe pressure of the medium under pressure is made fully available for forcing up the upper portion of the prop and no part of the pressure is lost in overcoming the ow resistance in the check valve. Furthermore, the arrangement provides a possibility of reducing the total length of the prop to some extent before setting it up afresh. For this purpose the connecting member can be attached to the prop and, by pressing it slightly, the check valve can be opened for a brief period without the pressure medium valve in the connecting member being opened at the same time. A part of the pressure medium contained in the prop then discharges through the open check valve to the outside and the upper portion of the prop correspondingly can sink lower into the lower portion.

The procedure followed in knocking away or robbing the prop is similar. In this case, the control of the discharge of the pressure medium is conveniently effected by a second double-armed lever which is also guided on the prop and lifts the check valve from its seating when the said second lever arm is swung by a robbing cable for example.

By using props made in accordance with this invention the development of a mine working can take place so rapidly and with so little trouble such has never been possible hitherto. At the same time it is ensured that all props are set with the same initial pressure, so that the roof is supported absolutely uniformly. If the roof subsides, the props are shortened, but at the same time the carrying capacity of the props increases up to a maximum value which can be adjusted by suitable choice of the excess pressure or relief valves. The knocking away of the props is carried out just as quickly as the erection of the props. It is unnecessary to actuate the discharge valve by hand, since the lever connected with the robbing cable and pivoted on the prop automatically opens the check valve when suicient tension has been applied to the cable.

A further feature of the invention consists in that the prop is provided with a handle above its centre of gravity. The handle conveniently is.so constructed that it can serve simultaneously for the mounting of the filling or robbing means. makes it possible for the prop to beeasily transported, especially in narrow mine galleries. The prop does not have to be carried as a whole, but rather is it intended that that the handle should be grasped in one hand and the prop moved backwards and forwards with the` foot end sliding on the door. Therefore, only the head weight of the prop has to be raised and the man has his other hand free in order to support himself on the coal face on the conveyor or elsewhere.

One constructional embodiment of the inventionv is shown, by way of example, in the accompanying drawing, wherein:

Fig. 1 is a plan view of a mine working, on a greatly reduced scale;

0 the prop also being shown; and

Fig. 4 shows the robbing means, also in section.

The arrangement of the handle Referring first to Fig. l:

The coat being worked in the mine working is freedV by a plane-like device 11 and automatically loaded onto the conveyor 12, which in turn carries out the cut coal to thedrift conveyor 13. The coal face is free from props. With progressive exhaustion, the conveyor 12 is continually displaced towards the coal face 10 over its entire length by the aid of return cylinders (not shown) or in any other suitable manner.

The exhausted part of the seam is supported by props 14 arranged in rows which form an angle with the coal face 10 and which are consequently arranged in saw-tooth formation, as will readily be appreciated from the drawing. The setting up of the props in the desired sequence is effected by connecting them, by means of a pressure hose 15, to a pressure medium piping 16 extending alongside the conveyor 12. The piping 16 is provided at certain intervals with coupling points 17 to which the pressure water hose can be' connected. The water under pressure may for example, be supplied from a iloor at a higher level if conditions inthe mine allow of such a possibility. It is, however, also possible in the vicinity of the coal face, to arr-ange a pump 18 operated electrically or byvcompressed air for supplying water under pressure. When the coal face 10 has moved suiciently far forward, the props 14 at the back are knocked away, whereupon the roof collapses or rests on the waste that is introduced. The hydraulic prop 14 consists of 1a lower portion 19 actmg as a cylinder in which is slidably mounted the extensible upper portion 20 as a tight-fitting piston. The lower and upper portions 19 and 20 of the props may be provided with a foot 21 and a head 22, respectively, these conveniently being constructed as ball joints, in order that the buckling-forces acting on the props are kept aslow as possible.

Provided on'the lower portion 19 of the prop are ft'rstly a check valve 23 for filling the prop upon setting up and for emptying it when the prop is to be knocked away, and secondly an excess pressure valve 24 for setting the maximum load. The valves 23 and 24 are located and are partly protected, between two plates 25 welded on to the lower portion of the prop these plates being connected together by a bolt 26 which is formed as a loop handle lying above the centre vof gravityl of the prop and thus making it possible for the prop to be easily handled.

Fig. 3 shows details of the valves 23 and 24 in section. Arranged in the valve 23 is a valve 27 in the form of a ball which is under the action of the spring'28 and is forced against its sea-t by the spring 28 against the pressure of the inowing water under pressure. This water is supplied through the hose 15 from the pressure piping 16 extending alongside the conveyor 12. The hose terminates in a connecting member 30 which is made as a double-armed lever and which, by means of a hook 31, is connected to the transverse bolt 26 of the prop. The longer limb 32 of the connecting member is formed as a tube on to which the hose 15 is connected and which serves as actuating handle. The second lever arm is essentially shorter and contains an outlet opening 33 for the water under pressure which is supplied. 'Ihe outlet tube 33 terminates in a pin 34 and in addition is enclosed by a packing collar 35. The connecting member Aalso contains a blocking or shut-'off member 37 which can be raised from its seating by a striker pin 40 upon moving a handle grip 38 in the direction of arrow 39.

If a pit prop 14'is to be set up, the connecting member is hung on the prop in the manner indicated in Fig. 3. It the prop is still somewhat too long, some watercan be discharged therefrom by slightly pressing down on the tube arm 32 in the direction of the arrow 41. The pinV 34 0f the connecting member actually Ais so long that when the tube 32 is swung round in the direction of the arrow41, it has already lifted the valve body 27 from its seating 29 before the packing cone v35 'has come to rest. In this condition, a part of the water under pressure can escape fromV the prop through the opened check valve 23, whereupon the upper portion 20 slides down into the lower portion 19 or can be pressed down by hand without effort. As soon as the prop 14 is set up at the place required, the tubular arm 32 is forced further downwards in the direction of arrow 41, so that first of all the ball valve 27 is lifted still further from its seat 29, but at the same time the packing cone 35 bears against and forms a seal with the conically ared surface of the check valve 23. If the handle grip 38 isrthen raised in the direction of the arrow 39, the pressure medium flows with great velocity from the pressure piping 16, through the hose 15, the tubular handle 32 and the small outlet tube 33, past the valve body 27 and into the cylinder space 19 of the prop, thereby forcing the piston-shaped upper portion 20 of the prop 14 against the roof with a force corresponding to the hydraulic pressure. In practice, the filling of the prop for its erection can take place in a few seconds without any fatiguing pumping work having to be carried out by the men. The prop then supports the roof by a force which is calculated from its piston cross-sectional area and the pressure of the water that is introduced. The prop remains standing in this operative position and the connecting member 30 can be disconnected and employed for setting up another prop.

With thelowering of the roof, the pressure of the water rises, since initially it is not possible for any of the water to escape, because the valve 27 has been located firmly against its seat 29 under the influence of the spring 28 and of the water under pressure. However, any damage or destruction as the pressure progressively rises is prevented by the pressure-relief valve 24, the valve body 43 of which, under the loading of the spring 44, closes a small opening 45 on the outside. By the loading of the spring 44, it is possible to regulate the pressure at which the water under pressure automatically escapes from the pit prop and the spring therefore fixes the maximum load of the prop.

If the prop is to be knocked away, then a double-armed lever 46 (Fig. 4) can be used for this purpose. The lever 46 is connected to the bolt or handle 26 of the lower portion 19 by means of a hook 47 and carries on its short lever arm 48 a pressure pin 49 which opens the check valve 23 when a pull is exerted on the longer lever arm 50 in the direction of the arrow 52, for example, by a chain 51.

As soon as the pressure medium escapes from the prop, the upper portion 20 sinks into the lower portion 19. When the prop is more or less completely discharged, it can be pulled underneath the roof to be protected by the aid of the chain 51. There is thus no danger of any kind for the robbing party.

What is claimed is:

A hydraulic pit prop having a cylinder lmember and a piston :member extendable therefrom, a pressure butt-type hose coupling element defining a fluid passage into said cylinder and defining a contact seat for pressure-tight connection with a pressure hose nozzle pressed in contact therewith, a check valve positioned in said coupling in pressure-tight closure thereof for opening actuation upon pressure of a. member inserted into said coupling, and means defining a fulcrum element positioned for pivotal attachment theretov of a lever arm of a member to be inserted in said coupling; and in combination therewith a pressure :hose `nozzle having an elongated rigid discharge nozzle with the end thereof dimensioned for pressuretight connection with the contact seat of said coupling clement upon being pressed in connection contact therewith, a rigid member extending from said nozzle for opening actuation of the check valve in said coupling upon connection contact of said pressure nozzle and said coupling, a short lever arm rigidly connected near the discharge end of said nozzle for pivotal attachment to said fulcrum element, and a prop-robbing device having a exible pulling element having attached to one end thereof means defining a member for insertion into the coupling element of the prop, said member having a hooked lever arm rigidly attached thereto for hooking into pivotal at- 5 tachment to the fulcrum element of the prop, whereby, upon the pulling of said flexible pulling element, said lever arm pivots on said fulcrum element, causing said member to press against the check valve, causing opening actuation thereof, and said lever arm remains attached l0 to said fulcrum element for the dragging away of the prop.

References Cited in the le of this patent UNITED STATES PATENTS Great Britain May 3, 

